The proposed research will demonstrate the feasibility of modifying the handling qualities, safety and efficacy of a proven transdermal jet injection system, the Medi-Jector EZ, for use by children and adults in rehabilitation, whose health and well being depend upon regular daily administration of transdermal injections. This project will produce prototypes of a dry disposable head assembly and an ergonomically modified power pack which are manufacturable within economic constraints and which satisfy design requirements identified by users in rehabilitative environments. Of particular significance is the safety, portability, flexibility and current widespread use (over 36,000 worldwide) of the patented Medi-Ject systems, approved for insulin and lidocaine. The Medi-Jector EZ uses an internal spring for pressure and requires no outside power, batteries or gas cartridges. Settings, with audio and visual calibrations, provide the pulse pressure and dosage adjustments. Med:-Ject's devices are mechanically unique and advantageous with respect to peak pressure routinely possible (16,000 psi), pressure flexibility (2,500 - 16,000 psi with 14 pressure levels), pressure adjustment possible without disassembling of device, and safety of medicament loading (no exposed needles). Subsequent phases will produce the modified devices, as well as educational support, for application in rehabilitation settings.